


Throwing Physics Out the Window

by TheWhiteLily



Series: Season Four Premiere Flashfic [15]
Category: Sherlock (TV)
Genre: Actual Physics, And then some more things, Breaking the Fourth Wall, Crack Treated Seriously, Dodgy Physics, Episode: s04e03 The Final Problem, Explains some things, Gen, Humor, In the same way that a photon is both a wave and a particle so this story is both a fic and a meta, Missing Scene, Serious treated crackily, Sometimes it can get tricky to tell which is which, slowly, sweariness
Language: English
Status: Completed
Published: 2017-02-03
Updated: 2017-02-24
Packaged: 2018-09-21 17:25:29
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 5
Words: 11,094
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9559565
Author URL: https://archiveofourown.org/users/TheWhiteLily/pseuds/TheWhiteLily
Summary: How to survive jumping out the window of 221B ahead of a grenade, in five complicated steps.(Or: Lily missed out on membership in The Empty Hearse club due to unavoidable circumstances, but if she’d had the chance, she would have been a vibrant and enthusiastic contributor. And possibly also worn the hat.)"I laughed until I had serious breathing problems" - IshtarsDream"God I love this on so many levels." - SherlocksSister"You are now officially my favorite person on the internet" - Dodoa"Oh my God. I cannot tell you how many times I burst out laughing." - Aelaer"Touch the physics and I’ll tell you the truth. I’ll touch it too, if you’re scared." - Eurus"A tedious and uninspiring effort. Give me back my hat. SH" - Sherlock





	1. Take 1

**Author's Note:**

  * For [Aelaer](https://archiveofourown.org/users/Aelaer/gifts).



> ... who may have created a monster with this particular request. Not sure if it’s precisely what you were expecting--or even quite fills the brief--but inspiration is a fickle master. And a thing’s not worth doing, I’ve always suspected, unless you _over_ do it.

The words flashed through Sherlock’s mind again: I owe you a fall.

He was falling again, arms and legs spiralling instinctively for purchase out to the sides… falling, _falling_.

But it wasn't the fall that hurt, it was—

And then he landed, face-first into something soft, which opened up beneath him and swallowed him whole. Gasping, the breath forced out of him even in the cushioned impact, he fought his way to the surface and raised his head above the cloth bags stamped with  _Soft Clean Express_.

“John?” he called.

He managed to climb to his feet, slewing sideways on bulging bags that gave and rolled underneath his feet towards the edges of...

_Metal box, open top, corrugated sides, laundry company._

The entire box accelerated, fast, making Sherlock fall backwards and forcing him to fight his way upwards again through the bags of laundry to avoid being suffocated.

“Stop the van!” he yelled, finding his feet again, wading forward. He hammered on the side with his fist and kept on hammering, using the side of the van to balance as the bags rolled beneath him. “JOHN!”

“I’m all right!” came a muffled voice from not too far away. “I landed in… bags of laundry?”

“STOP THE VAN!” repeated Sherlock, emphasising each word with a hammer of his fist on back of the cab. The last word echoed louder as the van pulled abruptly to a halt.

Ten seconds later, the tailgate opened, spilling out heaps of bags and a severely rumpled Sherlock.

“Hey!” yelled the cross looking man in a blue jumpsuit who was looking down at him. “What the bloody hell were you doing in there?”

Sherlock didn’t answer, looking up at the van behind, which had also stopped, its driver staring at him open-mouthed.

“My friend,” Sherlock gasped, waving his hand. He tried to get wobbly legs underneath him, and ended up sitting abruptly on top of one of the other bags. “Landed in the other one!”

He waited only long enough to see the other driver open his door and get out, looking baffled, before he tried to stand again.  This time he made it upright, staggering towards the pavement.

“Mycroft!” he yelled. “Mrs Hudson?”

Two slightly smoked looking figures made their way around the side of the building, the taller one holding a shepherding arm around the other, who seemed to be repeatedly slapping at his chest with both hands in protest and berating him.

“We’re fine,” managed Mycroft between coughing and flinching from the weak, insistently aggravating blows. He turned to looked down his nose in bemusement at Mrs Hudson.

Sherlock let the assault pass without inquiry—it was more than likely well deserved—but breathed a sigh of relief as he made it to the kerb and looked along the side of the second van to see John, a little shaky but none the worse for the wear, extracting himself from the pile of spilt laundry on the road.

“What just _happened_?!” John demanded, wild-eyed. “That was _way_ beyond lucky, Sherlock!”

“Are you all right?” Sherlock asked.

“Yeah, you?” John gave him a visual once-over to check, but accepted Sherlock’s confirming nod.  He shook his head in disbelief, then headed over to check on Mrs Hudson and, with all due reluctance, Mycroft.

Sherlock whirled on the driver of the van—the first one—who’d started haphazardly tossing back the bags that had fallen out along with Sherlock.

 _Smoker_ , appeared written in his hand. _Married_ , up along his ring finger. _No children_ , on the smooth, unwrinkled skin beside his eye. _Large dog_ , was along his hip. _Doberman_ , beside the distinctively coloured strands of hair. _Low on cash_ , appeared on the faded, threadbare collar of the shirt he wore beneath his company jumpsuit.

Nothing telling.

“Why were you parked there?” Sherlock demanded. “Right then and there? Tell me!”

“Couldn’t say, mate,” shrugged the driver, reloading the last few bags. “We drive along here every morning, round this time. Yesterday some bird at the hotel slipped us a fifty each to loiter a few minutes in line with those windows—” He swung the back closed and turned to point at the window of 221, eyes a little agog at the flames licking up out of it. “—round nine this morning. Said I’d know when it was time to move on. When that place went up, I knew all right! Oi, this wasn’t, like, a terrorist attack, was it? You’d never have known she was one of them, she wasn’t wearing no scarf or nothing!” He looked suddenly more frightened than amazed. “‘M I involved? I swear, I didn’t know! Only this load’s due at the Savoy by half past, and there’ll be hell to pay if they don’t have clean sheets come room service time.”

 _Two previous warnings for tardiness_ , appeared in the stress lines beside his left eye, and on the other side: _Needs this job._

Sherlock glanced at Mycroft, sidelong, who gave a defeated wave with his free hand—he’d managed to extract himself from Mrs Hudson’s grip only for John to take charge of his arm and begin putting it through a complicatedly doctorly series of motions. At least his brother agreed: there was no point detaining the drivers further. If Eurus was as intelligent as Mycroft said, she wouldn’t have left them anything to go on with these poor fools. They’d just be wasting time when the only productive thing they could do would be to go straight to the source.

“No, no,” Sherlock told the man, shaking his head. “It was just an accident. My flatmate there got careless with the gas burner.” John looked up from where he was manipulating the bones in Mycroft’s wrist to shoot him a dark look, but didn’t protest. “Lucky thing for us you were here. Have a good day.”

Sherlock stalked over to the other three, ignoring the drivers exchanging a look of mutually terrified agreement, half-running to their cabs and speeding away.

“Well,” he told them. “It seemed likely given the fact that her explosive didn’t detonate immediately, but now it's unmistakable that she doesn’t want us dead.”

“Nor either of _you_ , at least, seriously injured,” put in Mycroft, wincing under John’s ministrations.

“Not yet, anyway,” added John grimly, then dropped from cynicism into his brisk doctor’s tone. “Nothing broken, minor strain on that elbow,” he said. “It should come good within a few days. I can strap it if that would make you more comfortable, but mostly you should just take it easy and try not to do anything that hurts, all right?”

“Thank you, Doctor Watson,” he said noncommittally, reclaiming his arm and standing up straight.  

He eyed the minor rumples in his suit with the disappointed air of one who lived in every expectation that even clothes would fall into neatly pressed line if he simply _looked_ at them enough.

“Well, if it’s my attention she wants," he added, "she now has it in full.  If you’ll excuse me, gentlemen, Mrs Hudson." He nodded to each of them in turn. "I’ll leave you in the capable hands of emergency services. I’m sure you understand that I have some urgent phone calls to make, and some new holes to _rip_.”

A sleek black car pulled up at the kerb beside them, just as two fire engines and an ambulance did the same further down the street, outside 221.  Mrs Hudson, apparently quite recovered, gave Mycroft's retreating back a final glare and hurried down to see about the state of her home.

Sherlock exchanged a quick mutual glance with John: raised eyebrows, a tiny nod. He hurried over to grab the door of Mycroft's car before it could close.

“Come on, Mycroft,” he said.  "It's not _your_ attention she wants, clearly.  If you try to go anywhere without us, there'll probably be more explosions."  

Sherlock looked at his brother for a long moment, until he got a sideways tilt of the head in concession.  He opened the door wider to let John in ahead of him—it was always a good idea to have some kind of a buffer zone between himself and Mycroft—but before following he looked up at the window once more… and then down at the road where the laundry vans had parked.

“Wait,” he said, then looked back to the window—to the road—to the window.

In his mind, the image of a man formed, arms and legs windmilling as he jumped out and arced—kinematic equations spilling out behind him to inscribe a perfect parabolic curve in the air—gracefully falling towards the waiting van…

 _… d = v i t + ½ a t 2_, wrote its way down the wall of 221B from the railing of the balcony towards the paving stones below, _a = 9.8 m/s 2, vi = 0, d = 3.5 m, t = …._

There was a brief pause as the number filled itself in.

_… 0.85 seconds._

The equations started arraying themselves horizontally this time, starting back inside a cutaway section of 221B's wall where a second figure was running, leaping from the chair to the windowsill and then pausing as its foot left the ground to hurdle over the rail.

 _… v i ~= 5m/s_, appeared hanging over the figure's head, and then out into the air continued, _a = 0, t = 0.85s, d = …_  

Sherlock frowned as the latest number appeared, and then rewrote itself on the paving stones three metres from the wall, well short of the kerb.  The parabolic curve readjusted itself to match, and on the street, several metres further away, a ghostly laundry van revved its engine and drove away, completely empty of anything but its ordinary load.

“No,” he said, shaking his head. “No, this doesn’t work. The angle’s too stee—”

...  _Sherlock!!! See, this is the problem with you as a narrator. You_ never _cooperate. You see a loose thread in a perfectly good story, and you just have to_ pull _on it, and keep _pulling_._

_Look, all right, okay.  If you insist, I’ll check the footage._

_Rewind. Play. Blah blah blah, ‘good luck boys’, countdown, running jumping exploding…._

_Bugger._

_Hubby? Can you double check some intuitive physics for me? Yes, I_ know _I beat you in the race to second place in high school physics, but I didn't exactly top the year, did I?  Besides, I can’t catch a ball to save my life, will you just look? Yeah. They’ll land right there, won’t they, near the edge of the pavement. Blank, featureless concrete tiles. No laundry vans. No air bags. No Speedy's awning. No troupe of French mime artists holding up a sheet of tissue paper over a humorously oversized tub of custard._

_We can see. Exactly. Where. They’ll. Land. In shot. On the concrete. Right there._

_Bugger._

_Why, Moftiss, why do you make this so hard._

_Okay. Back it up, let’s try again. No more narration from you though, Sherlock; I’m not risking that happening again._

_No! I don’t want to hear it! No more physics! You're not the only one with traumatic memories from your childhood! Some of us don't get to delete those things, we just have to_  live _with the memory of having come in..._ second _. Ugh. There's a reason I'm a writer, not a rocket scientist like bloody first-in-class Hung Wang turned out to be. Just… just do as you’re told this time, and no one has to get hurt.  All right?_

_Right.  Everybody ready?_

_And… action!_


	2. Take 2

It was two weeks since Dennis Trellik had finished work “fixing up the cracks” in the pavement outside 221B Baker Street, with his team.

It had been a sweet job for an out of work mining engineer—paid incredibly well for a few days surreptitious work—but he’d probably have done it at cost, just for the chance to work on something like this. Still, given she'd offered, he certainly wasn’t going to say no to a bit of money: anything to put off the necessity of going back to working for some mining corporation that asked him to solve a problem and then couldn’t accept the elegant beauty of his _vision_.

He’d needed the downpayment, anyway, to cover acquiring materials. Illegal C-4 wasn’t cheap, even the tiny amount he’d needed, even for a guy who knew guys in every mine all over the UK. And there’d been a progress payment at the end of the installation: more than enough to pay off the labourers he’d hired to assist with the digging and to stand around eating sandwiches and leaning on shovels so they all looked suitably like official government employees. The final ten thousand pounds of pure profit would come through after the successful operation of the device.

But it wasn’t the money that had made Dennis restless and unable to relax in the intervening weeks, until it was finally the time she’d given him to pop by and pull the safety pin from inside a nearby drain. It was a matter of professional pride.

Technically, at this point, he was supposed to clear the area, but…

Well, it was a once in a lifetime opportunity to see something like _this_ in operation. It had never been possible to test it. For obvious reasons. Although he hadn’t needed to; when something was set up right, it worked. If it wasn’t set up right, then what had been the point?

Still, there was no _way_ he was going to miss watching it—whatever 'it' was—happen. Besides, he’d held onto the traffic cones they’d used to block off the street during installation, and he’d brought them along today, set them out along the opposite footpath to minimise pedestrian traffic beneath the windows of the building marked 221B. Wouldn’t want anyone to get hurt, after all.

He wasn’t sure what, precisely, to expect, but he’d been rather good at high school physics, after all, and—

_… absolutely not! No physics, Dennis!_

He wasn’t sure what, precisely, to expect, given the complete and utter lack of knowledge in the physical sciences that had always made him so good at his job. Guessing and trusting his gut had always worked much better for designing complex interactions between objects in motion than using known laws of the universe to predict anything at all—

 _… Look, Dennis. You’re the one who waltzed into my brain wanting a point of view part, despite a complete lack of experience, and I gave you a chance. Now_ please _, we don’t want editorialising, just… focus on dumping the information the reader needs, before '_ _it'_ _happens, all right? You don't have long...._

He wasn’t sure what, precisely, to expect, but he’d been the one to install the seismic trigger on the device, after all, he’d be lying if he said he thought there wasn’t likely to be some kind of—

There was a deep, concussive _whump_ that shuddered through the ground and momentarily unseated his stomach.

—explosion. Ah, that certainly took him back to his days working in the mines.

Although mine explosions didn’t usually blow out windows, like had happened to the ones across the street. Mostly because there didn't tend to _be_ any real-glass windows within blasting distance.  As he glanced up, he could see the shards of glass shattering outwards, ahead of the forms of two men, falling directly—oh wow, _directly_ , was _that_ was what all this was for?— _directly_ for the precise paving tiles he'd put so much work into… where now something was starting to take place.

Dennis’s eyes fixated to the mechanism he’d installed, willing the thing of beauty that it was to work.

The overpressure wave from the explosion had rocked the ground, triggering the vibration-sensitive release switch and—as the two men above cleared the railing and began to fall—two identical squares of four adjacent paving stones in line with the windows began to fall too, the thin cosmetic line of grout that had disguised the junction with their neighbours cracking away, as they dropped a crucial ten centimetres in perfect synchrony with the men above.

Unlike the men—who continued falling, accelerating towards the ground under gravity’s pull—the paving stones thunked to a halt there for a few milliseconds, held up by a pair of supporting rails. The contact connected a pair of red and black wires, and closed the electrical circuit.

A pulse ran from a battery along the trigger wires into a blasting cap, carefully embedded within a scant line of plastic explosive. Two weeks ago—after capping two steel plates with enough concrete to _look_ like paving stones and setting them into place—he’d carefully smeared the explosive along the faces between the seam, set the fuses in place, and applied a thin decorative layer of cement to cover it all it. And then repeated the whole process, a couple of metres over.

Hit by the charge from the trigger wires, Dennis's explosives detonated. Tiny amounts though they were, the blast cracked the apparently sunken squares of pavement into two halves along the middle and sent each half rocketing in opposite directions, into the spaces he’d hollowed out underneath the neighbouring paving stones as smoothly as though they were—as was in fact the case—on greased rails.

The paving stones reaching the end of their rails with a crash, and had just disappeared entirely by the moment the two falling men touched down, each in the _exact_  centre of one of the holes.

Dennis grinned widely, flushed with perfect success of it all, as they both landed, feet first, into the holes that had opened up beneath them and, looking entirely astonished, sank half a metre into the pavement before bouncing straight back up into the air.

That would be the under-pavement trampolines he’d installed in the holes.

“What the _hell_?!” demanded one of the men, still in mid-air. He landed on the pavement, his momentum having carried him further forward and off the trampoline. He thudded into the side of a parked car, staggering a bit and still staring down at his initial landing place in shock. “No _way_ , Sherlock! That was _not_ here when I arrived this morning!”

“Extraordinary,” breathed the other, who’d also jumped off and knelt to examine the mechanism. “The slabs are still there, underneath the ones next to them. There must have been a shock sensitive trigger—something to activate it at the right moment, drop them down, a small amount of explosive—the crack marks here, smell of C-4—to propel the segments apart fast enough to expose… _this_.”

He sat back on his heels, gazing at it in wonder. Dennis felt pretty chuffed to have someone on the scene who obviously appreciated the genius of his creation, but he tried not to look too interested, drawing back within the gathering crowd of gawkers. He wasn’t meant to be here at all anymore, after all, even if she obviously hadn't expected anything else.

“How long has it been there?” demanded the standing man, who was glaring at the trampoline that had caught him as neatly as a basketball in a hoop, as though it had personally insulted him.

The taller one shook his head. “They did some unnecessary work repairing the pavement here two weeks ago. I was…” he glanced up at the man next to him, “… otherwise occupied at the time. I _had_ assumed they were Mycroft’s men, doing his dirty work, but of course it’s always possible that I blamed the wrong sibling.”

“Two weeks ago,” said the other one flatly. “You’re saying, Sherlock, that your _psycho_ sister so perfectly predicted our positions in the room up there, our actions, our trajectories out of the windows, that _two weeks ago,_ she installed….”

He gestured helplessly at the miniature trampoline, as though words failed him. Despite the seeming ingratitude, Dennis had to admit words had failed _him_ when he’d first seen the plans for the thing, too. She was a proper genius, that woman.  And quite a looker, too.

“ _Two_ weeks ago,” the same man repeated. “Not one, not three. _Two_. That was, that was a _week_ before we had that conversation in her office. Sherlock, that’s _insane_.”

“I _know_.” The man on the ground looked up at his companion with fever-bright eyes. “Oh, John, I can’t _wait_ to meet her!” His face twitched. “Again.”

Then he looked down, his eyebrows furrowing as he looked down at the mechanism again.

“No, wait a moment,” he said. “ _I_ was a distracted two weeks ago, but…”

He looked up again, and Dennis followed his gaze to a CCTV camera at the end of the street, pointed directly at the cafe and front door behind him.

 _She_ hadn’t warned him about _that_ , which was surprising given how obviously intelligent she was.  She'd probably topped physics class, with that kind of mind.  Or at least come in second.

_… Dennis…_

Had he been recorded on camera installing this thing? Had she forgotten about it? It was her story, after all, and she wouldn't have just glossed over something like that....

 _... Dennis, it was_ Eurus _that hired you, not me! Stay in character!  Keep it together!_

“What was _Mycroft_ doing while they were putting this thing on?” the dark-haired man scoffed. “Watching me like a _hawk_ , that’s what.” He looked disturbed for a moment. “Sometimes quite literally. I can assure you he won't have missed a company of fake roadworkers.  No, this is utter bollocks. _Anderson_ -level bollocks. She simply _can’t_ have—”

_Aaaaargh!_

_Damnit, Sherlock, I told you to leave my story alone! This is… it’s… *flails* …perfectly believable!!! In every way!_

_Because I say it is, that’s why, and it’s my story! Of course Eurus could have calculated the precise landing point! And designed and arranged installation of an elaborate machine! Who doesn’t like greased rails? More explosions! Hollowed out underground pockets! And the trampolines, they were cool, right? Of course he could have done all that without looking like he was doing anything fishy and then covered it up so that it looked normal enough on the surface to fool a cursory glance from Sherlock, all without attracting any notice from the all-seeing eagle-eye—or at least drone-eye—in the sky of Mycro—_

_Ah, fuck it. You’re right. Fine. I can’t even convince myself. This is bollocks. Dennis, you’re fired; you were a rubbish narrator anyway._

_Okay. All right, nobody panic. We can totally do this. So they can’t land on anything but the pavement. And sadly, at the point of impact, that pavement is entirely normal, 100% hard as a rock concrete._

_Unless…. Oh! Oh, that’ll work. I’ve got it._

_Shut up, Sherlock, nobody likes physics._

_Let’s try again. We just need to back it up just a_ _bit further. And I think it would be safest if we looked through John’s eyes from here on in: someone with a bit more practice won’t be so difficult to work with. He studied nice, squishy biological sciences, so he should be much more malleable. Besides, I’ve been told he’s an idiot._

 _It’ll be_ perfect _._

_Places everyone, and… action!_


	3. Take 3

John counted seconds in his head as he turned and ran—faster, faster, have to reach cover—Mycroft had said at most three seconds. That was hopefully enough to be out the window and below the level of the wall, probably even enough time to make it to the ground outside.

_One._

He was passing the side tables, reaching the window frame. He leapt forward, his foot reaching towards the stack of books under the window, just starting to think about turning to take the impact of the glass on his shoulder and covering his face to protect it from the shards—as though that was his biggest problem—when…

_Two._

_Whump_.

Bugger, John didn’t have time to think, because he didn’t have any time at all.

It hadn’t been three seconds after all, which was a shame, because now they were all dead.

The window shattered in front of him as the shockwave hit with a sickeningly familiar _thud_ to his organs and an intense stab of pressure in his ears, which hurt, but held. An overpressure wave of around 2 psi then, to blow out the window and yet avoid severe structural damage the walls—at 3 psi, they would have collapsed, and no one wanted that to happen to Baker Street. Windows were surprisingly strong.

_… John, please stop talking to the camera._

As were human bodies, being more flexible and thus more resilient to change in pressure than a rigid structure like a building. Eardrums didn’t even start rupturing until 5 psi, while fatalities from injuries such as severe blast lung were likely to occur at more like 75 psi. The walls were fine: so were their innards—at least from the  _first_ of the dangers of a grenade.

 _… I’m warning you, John. You don’t know any physics. You were a_  doctor!

He’d had bad days. Days when the thought of physics had been his only—

_… Oh, for God’s sake. Next story I’m going to make you so fucking oblivious to whatever Sherlock’s up to that people are going to think you’ve got brain damage. Just… will you focus, please, on getting away from this explosion?_

John put every last inch of his energy into making it as far away as he could from the explosion. He wished there was a possibility the force of the blast might pick him up and toss him further out of range—but in fact at this distance there would be very little physical effect on a large object like a human—the kinds of shockwaves that threw bodies around were the kind that also liquified your internal organs.

_… John, seriously, stop it. Even in slow-mo, there is literally no time for you to do any kind of narration in the _milliseconds_ during which this is happening, not to mention that you have _no_ idea the kind of research into explosives you’re making me put on my Google history! I’m probably on every terrorist watch list there is at this point, and it’s all your fault! Besides, you’ve got bigger issues to worry about than the shockwave._

Still, John had bigger issues to worry about than the shockwave.  At every moment, even the ones that went by too fast to narrate, he anticipated the feeling of a hundred white-hot pokers to piercing him all over, perforating every internal organ in multiple places as the grenade fragments hit.

John had operated on grenade trauma before, too many times. Once would have been too many. At this range, though, and with no cover, not a one of them would make it to the operating theatre. They weren’t even _close_ to far enough out of the kill zone—and they were entirely without cover, the full surface area of their bodies exposed to the bast. Within five metres was instant death, within fifteen, severe injury was unavoidable. John had pulled fragments out of people standing two hundred metres away from a grenade going off.

Fragmentation grenades were fucking scary.

_… You’re not kidding, John! So unless you’ve got a solution, you can bloody well shut up about it, and we’ll hope they don’t notice!_

If, of course, it was a fragmentation grenade, which was seeming less and less likely with every passing millisecond.

_… Oh. Oh! Clever, John! I see why Sherlock finds you useful. Carry on, then._

John was already travelling up, up and over the railing as the heat of a fireball assaulted his back, reaching out for him hungrily but not _quite_ grasping him. Which of course, explained the lack of fragments peppering his body at half the speed of sound and the accompanying instant death.

No standard grenade produced a fireball like that: just dust, demolition, and dead and bleeding victims. This wasn’t a fragmentation grenade after all.  An offensive concussion grenade would produce all the shockwave and more of a standard grenade, without the lethal fragments.  An incendiary grenade—the big brother of a molotov cocktail—didn’t explode in a technical sense, as the deflagration travelled at subsonic speeds, but would certainly set everything in the vicinity on fire.  

This device was obviously... some kind of combination of of the two, the concussion grenade’s casing perhaps packed with petrol that aerosolised and then ignited in the explosion.

_… Yes!! _Thank_ you, John!_

He did wish Mycroft had mentioned that.

_… Bugger. Why wouldn’t Mycroft have mentioned that?_

Although perhaps Mycroft hadn’t known. They’d announced a new grenade developed by the US Military which hadn’t been released for general use in John’s time, that allowed the user to choose the mode—fragmentation or concussion—when they armed it. As well as adjusting the time to detonation.

Perhaps this device was the ET-MP grenade's more advanced younger sister. Even if the size of the deflagration was slightly unbelievable compared to the size of the bomb itself. Then again… perhaps it was some new top-secret accelerant no one outside the British Government had ever heard of.  After all, it was _very_ clever.

_… Hah! In your _face_ , Mofftiss! Thematic references and everything!  And you thought we couldn’t make your dumb movie explosion work. John, you are officially my new favourite narrator._

It was looking ever so slightly more possible that they might just actually _live_ through this.

If only they could manage to handle the impact with the ground.

 _… Oh, don’t you worry about _that_ , John. After solving _that_ one for me, I’ve _ so _got you covered._

“GO GO GO!”

John had barely started to look up at the voice, registering the sound of a chopper and the high-friction whine of a rappelling line and a rope spilling to the ground, when there was a figure dropping quickly past his face, falling perfectly into place for him to crash into them, and grasp him under the arms.

Desperately and instinctively, John wrapped arms and legs around his black leather-clad rescuer like a terrified octopus, the two of them swinging together in a wild pendulum on the end of the line as the remainder of his forward momentum spent itself harmlessly.

“Oh my god,” breathed John, still trying to come to terms with being alive, and also, gradually, with the pleasantly curvaceous sensation of the body pressed against his.

… _Told you I had you covered, John. * _wink_ *_

“ _Muppet_ and _Bromine_ are secure,” muttered his rescuer, ignoring him. “Do you have _Antarctica_ and _Gorgon_?”

“Muppet?!” protested John, before a proper look at her face drove all memory of the code names out of his head. “ _Anthea?!”_

“All units proceed directly to the rendezvous point,” she muttered again, giving him a vague, unseeing smile.

The helicopter rose slowly, taking them up and making them spin crazily on the end of the cable. John clutched on to Anthea tighter as he realised she’d just actually _let him go_ without warning so she could pull a second safety strap from her belt, wind it around under his armpits and clip it on.

He felt a little better once he was properly tethered—better enough to look around to find Sherlock… who'd been caught by another woman on the end of a line hanging from the chopper’s other door. He seemed to be struggling, and yelling something incoherent about physics.

“ _How_ were you there at just the right time?” demanded John, turning back to Anthea. “That was _insane_!”

“I’ve been trained to anticipate the needs of Mycroft Holmes,” she said darkly, without looking at him. Now that he didn’t need her to hold onto him anymore, she’d pulled a phone out of some kind of pocket in the space-time continuum—it certainly couldn't have been her trousers—and was texting, despite the wind tearing at them. “It requires special skills.”

When John continued gaping at her, she gave him the patient look one might give to some who, despite your best efforts at education, remained every bit as stupid as the first time you’d met.

“I planted a bug on him,” she said, returning her eyes to the phone. “Four minutes to scramble a helicopter in central London is child’s play; I spent most of the time changing into a more practical outfit.”

Involuntarily, John’s eyes darted downwards at the generous cleavage half-exposed between the two halves of the zip, further down the tight curve of the leather over her hip, further down at the six inch heels on her boots.

If this was practicality, he _liked_ it.  He was a widower, not dead, after all.  And apparently the author thought he deserved a treat.

“Eyes _front_ , Captain Watson!” she snapped without looking up, startling John into immediate, wobbly compliance.  Some habits from Army drilling, you never forgot.

“… let me _go_!” Sherlock was yelling, his agitated voice just becoming audible over the noise of the chopper and the wind as they rose higher and swung towards the centre of London. “I refuse to be rescued in such blatant contravention of the physical laws of the universe! I’m making a citizen’s arrest! You’re being charged with crimes against reason, wilfully breaking the law of gravity, and the illegal detention of a falling body! You have the right to accelerate towards the centre of the earth at a maximum of 9.8 metres per second per second! You have the right to bring in a pocket calculator and a single page of handwritten notes! You have the right to a ten minute perusal during which you may make notes only—”

John exchanged a look with Anthea, who was looking put out.

“I wasn’t going to say anything about it,” he shrugged, trying not to be too obvious about looking down over her shoulder. “I’m happy enough.  That doesn't happen to be your twin sister over there, does it?”

“I _will_ drop you,” she threatened.

Sherlock, in response to something inaudible the woman holding onto him had said, exploded again, “Because apparently now instead of a witty BBC crime drama with intricate, clever detail and subtle, ambiguous character development, we’re starring in one of John’s bad American action movies that focuses on _blowing shit up!_ Using _appallingly bad physics!_  Still, I didn't think we were _this_ far gone.”  He looked the woman holding onto him up and down with an offended glare. “Not to mention that employing a deus ex machina is the sign of a _terrible writer_!”

_… Oooh, that’s… that’s a low blow, Sherlock. A very low blow. I’ve got to work with what I’m given, all right?_

_Okay, okay, look, you’re right, you’re absolutely right._ _One freefalling body, no matter how sleekly dressed, cannot catch up to another that started falling first. I know, okay? Sigh. At least John had fun. Next time, proper physics, I promise. I would_ totally _have topped the year if it weren’t for goddamn Hung Wang and his eidetic memory pushing me down to second, and Hubby to a miserable third._

_And of course the solution to a problem like this can’t just come out of nowhere; it has to arise naturally from elements already familiar to the audience. Damnit._

_Maybe I can’t actually fix…._

_No._ _No! I believe in Sherlock Holmes!_

 _We can totally do this. We’re half-way there. John’s worked out the whole explosion thing, thank God. (We just won’t mention the strange lack of effect of the shockwave on the rest of the more-fragile-and-far-closer-than-windows objects in the flat before the fireball hit them. Or the bizarrely intact floor, not that we’re mentioning it.  Because no one really wants 221B to suffer more than superficial smoke damage.)_  

_We’re a good team, John, you and I. We can find a way to solve this case! We just have to back it up a bit further._

_And as for you, Sherlock… zip it! I don’t want to hear a word out of you next chapter; I mean it. No narration, no dialogue. Not… one… _word!__

_Okay. Right, then. Think, brain, think: there’s got to be a way to make this work. If there weren’t a realistic way for it to happen, it wouldn’t be on TV. Certainly not as part of such a deeply serious, gritty, and entirely real-world program as _Sherlock_. _

_That just wouldn’t make any sense._

**Notes for the Chapter:**

> A very few selected research links:  
> [Effects of blast pressure on structures and the human body](https://www.cdc.gov/niosh/docket/archive/pdfs/NIOSH-125/125-ExplosionsandRefugeChambers.pdf)  
> [When a person is near an explosion does its body get pushed like in the films](https://www.quora.com/When-a-person-is-near-an-explosion-does-its-body-get-pushed-like-in-the-films)  
> [Explosive effects on buildings](http://www.stuvex.com/frontend/files/userfiles/files/explosion-effects.pdf)  
> [Waaay too much information.](http://publications.jrc.ec.europa.eu/repository/bitstream/JRC87200/lbna26456enn.pdf)  
> [The multi-mode grenade John mentions.](http://newatlas.com/us-army-hand-grenade-et-mp/45481/)


	4. Take 4

**Notes for the Chapter:**

> Thanks to Megabat for the beta and the reassurance!

_Five years earlier…._

The kitchen was on fire.

It had started small. Among the clutter on the kitchen table, a precariously balanced experiment—investigating the resistance of and thus protection provided by an overweight victim’s layer of fat against a belly stab wound—had fallen, tipping over a bottle of methylated spirits and the lit bunsen burner Sherlock had been using to—it looked like, toast marshmallows? Really?

John shook off the thought as the burning liquid flowed across the table, traversing the dirty dishes from breakfast, soaking into a teatowel, which caught fire along with the rest of the—yes, that was clearly a packet of marshmallows, was he _eating_ them? Was it for a case?—and pooled around the fatty tissue of the belly-fat experiment, melting it to mix in with the rest of the conflagration.

In a matter of moments, most of the table was ablaze, cascading a curtain of burning liquids onto the floor beneath, while Sherlock busied himself shutting off the gas tank still supplying the little tongue of flame that had started it all.  

In a corner of the ceiling, the smoke alarm began pealing out a deafening wail.

“Shit!” yelled John, his back against the pantry, staring at the mix of spitting hot sugar, melting plastic and scorchingly runny hopefully-not-actually-human tissue, trying to think what chemicals he could see and what would be the safest method to put out the whole mess.

His eyes focused on a large white plastic carton decorated with an orange square with a skull and crossbones, which was crammed onto the kitchen table along with everything else.

“The formaldehyde!” John cried. 

Christ, if _that_ went up they were in trouble—fire was already pooling around the carton’s base, that was _bad_ —but Sherlock was already diving for it, reaching through the flames with his bare hand to grab the handle and whisk it away off to the side.

His face turned white as the fire licked along his exposed arm, but he didn’t let go of the container, retreating out of range of the blaze and setting it down around the corner in the living room.

By the time he’d turned back again, John had pulled himself together and grabbed the box of baking soda out of the pantry. He tore open the top of the paper packet and stood closer, flicking it at the fire repeatedly, sending spray after spray of white powder over the blaze on top of the table and beneath—under heat, sodium bicarbonate consumed oxygen and produced carbon dioxide; it worked almost as well as a CO2 extinguisher—until the flames gave up and died out.

There was a moment of stillness, broken only by the continued piercing wail of the alarm, and then John and Sherlock both turned from the blackened and twisted wreck atop the table to stare at the whitish-grey burn that that stretched from Sherlock’s wrist almost to the elbow where he’d rolled up his sleeves.

Sherlock sat down rather abruptly on one of the kitchen chairs, cradling it.

“You’re okay,” said John instantly, understanding the shock response. The pain probably hadn’t properly kicked in yet, but it would at any moment now. He strode to the sink, lifting the dishes out onto the bench at the side as quickly as he could. “It doesn’t look too bad.”

By the time John had turned the tap onto full, Sherlock’s brain had kicked back into gear and he was standing ready to thrust his arm under the water, the tension in his features relaxing once the burn was under the cooling stream.

John left him to it for a moment and grabbed a chair to climb onto, popping the battery out of the smoke alarm so they could hear themselves think again, before he returned to Sherlock’s side.

They stood together for a moment, Sherlock turning his arm so they could both examine the burn more closely through the gushing water.

“It’s second degree,” said John, who’d seen more burns than many doctors. “But the skin doesn’t look broken, that’s good. You’re going to have a grand blister—and it’s going to hurt like the blazes for the next few weeks, but it should heal up fine if we keep it clean.”

Sherlock’s expression turned intrigued at the strange appearance of the burned skin, like loose grey elephant skin where the flames had touched him. God, John could see a whole _new_ range of burning experiments coming up.

“All right,” said John, after they’d both caught their breath and turned from Sherlock’s injury to look at the devastation of the kitchen table once more. “You stay there with your arm in the water—at least five minutes, I don’t care if you get bored. I’m going to start clearing this lot up. This could have been _so much worse_. If you’re going to do this kind of crazy stuff in our home— _marshmallows_ , for God’s sake, Sherlock, you didn’t even ask if _I_ wanted any!—we _really_ need to update our fire safety procedures. If that formalin had blown, it might well have blocked off the stairs. We need a proper extinguisher and a blanket, and we need to think about escape routes, too.” Not just for fires, now he thought about it. “We should have done that _ages_ ago.”

Sherlock made a face at the dull idea of safety planning.  Then he looked towards the living room windows, bored resignation falling abruptly from his expression. John recognised the glow in his eyes as the beginnings of a Plan.

Well, at least it was something to keep his mind occupied while he kept his arm under the water.

And really, how insane a plan was it possible to concoct in only five minutes?  Even for a Holmes?

After a moment’s thought, John felt very, _very_ afraid.

* * *

_Present day…._

John counted seconds in his head as he turned and ran, passing the armchairs… hurtling towards the windows…. He reached out one hand down and to the side as he ran, ready to brush the edge of the window-frame, hoping he would be able to—

But that fire escape plan had been made a long time ago. John didn’t even live here anymore, had barely bothered since the fall trying to keep up his ineffectual attempts to police Sherlock’s adherence to boring things like ‘gun safety’ and ‘not contaminating evidence’ and ‘having someone to watch your back’, let alone ‘fire safety planning’. Would Sherlock have kept the….

But of course he would have. It had been his plan after all. He’d been the one to order the equipment over the Internet, calculating lengths and breaking strains and installing anchor points; had set it up to make sure everything was tucked discreetly out of view of the potential threats they invited into their home, while John swore the whole thing was ludicrous and not a remotely manageable plan in the stress of emergency.

John and Moriarty may not have seen eye to eye on much, but his observation that Sherlock wanted everything to be too complicated was right on the….

_… John, this is what we’re going with, okay? The physics is totally fine, and I’m really running out of patience with the backchat. Have you forgotten what happened to Sherlock? Your flat is about to be consumed by a fireball. Watch your step, mister._

For his own safety, John tried not to think too much about the complexity of the plan, carefully watching the placement of each step as he fled.

He snatched the carabiner from its hook on the inside of the window frame and kept on going, leaping up and over a stack of books and out the window, the glass shattering in front of him in the shockwave just before he passed through.

In mid air, without stopping—and with _absolutely_ more than enough time to be certain that everything was safe and secure—he reached around and clipped the carabiner onto the back of his belt.

Then he was over the railing, in the air, and it was looking ever so slightly more possible that they might… just… actually… _live_ … through….

_… the camera cuts back from the fireball reaching still-intact objects within 221—not that we’re mentioning any physical issues with that—for a brief slow motion hero shot of our intrepid duo mid leap, the glass from the windows shattering and blowing outwards spectacularly in front of them, the hastily applied safety lines hidden between their bodies and the rails…._

_… and then another of them falling, the visual of the safety lines, again, obscured by flames licking at their backs…._

The line attached to John’s belt began to draw tight, the elastic cord giving more and more resistance as he fell, more slowly now, the increasingly insistent pull at his hips growing painfully tight, his body jacknifing in mid-air, folded almost in half around the incomplete harness until… barely a foot from the ground… he changed direction, bouncing back to soar upwards, his outward motion turning back towards the building… then he was on his way down again, colliding with the Speedy’s awning in perfect synchrony with Sherlock.

 _… take THAT Mark Gatiss, for your “Boop! And they’re fine.” theory of the Speedy’s awning far behind them breaking the fall. Oh, yeah, Mycroft is_ not _having a fun trip down the stairs for making me do that._

The red canvas crumpled under their combined weight and they fell another few feet, both hanging limply for a shocked moment like matched jellyfish on a pair of lines, still bouncing a little, barely a metre off the ground.

John managed to gather his wits enough to reach behind and pull the release pin on the carabiner holding him to his bungee cord, and landed in a crumpled—but relatively safe—heap on the ground. Sherlock did the same barely an instant later.

Released abruptly from the tension, both untethered cords pinged upwards like a pair of whips powered by the full stored kinetic energy of their body weights. John’s line carved a deep score in the brickwork of the top floor, Sherlock’s sank into the miraculously intact window of John’s room two floors above with a shattering _crack_.

They both ducked, shielding their faces from the shower of glass shards and brick dust raining down, as the bungee cords whipped back and forth again through the flames reaching out from the living room windows and finally slithered to a halt hanging half-way down the wall.

After a moment when nothing more happened, John looked at Sherlock, wondering what you could say after something like that had actually worked. He had to admit, he’d been dubious about this particular escape plan, but it seemed they’d actually made it to the ground unharmed.

Sherlock was obviously suffering from the same lack of words, because he stared back at John… and then his eyes dropped.

There was a considered moment during which he frowned, gazing at his hand miming a simple squeezing motion in the air. Then he reached around to touch that hand to his back, his expression growing less and less puzzled, more and more certain. He opened his mouth to speak—

_… Not one word, Sherlock, I warned you!_

—before apparently changing his mind and closing it again.

He gave a scathing glance at the camera, and then reached up and floofed his hair with both hands.

_… What the hell._

John’s breath caught in his throat as Sherlock leaned over towards him—

_… Sherlock. NO._

—reaching out to grasp John’s face with both hands, turning it to meet him—

_… Sherlock! I said NO! Have you not seen the tags on this fic?!_

—framing his features with long fingers, pulling him in for a….

_… ENOUGH! Cut! For God’s sake, Sherlock, you can’t do that sort of thing without appropriate tagging!_

_Seriously, let him go, he’s not—oh God, John, please, not you too. You’re_ not gay _! This is not a Johnlock story! I could have doubled my readership if I’d tagged it like that!_

Stop it _, John! This is_ so _not the time, people will talk! Now_ get  _your hands out of the back of Sherlock’s…_

_Oh._

_Okay, Sherlock, fine. Fine. You’ve made your point._

_Don’t look so disappointed, John. ‘Not gay.’ All right? Right._

_Now. Sherlock. Clearly this isn’t working for either of us. We wanted_ less _Anderson, not… *waves a helpless hand upwards* … all that._

_Quite obviously the biggest problem with this particular scenario for any true fan is this: Sherlock doesn’t actually wear a belt. His trousers don’t even have belt loops to attach one. And let’s face it, when they’re that closely tailored—_

_… pause for a moment of purely aesthetic appreciation of the beauty and exquisite economy of the human form…_

_… okay, maybe a couple of moments…_

_… I didn’t mean you, John, you're ‘not actually gay’, remember?_

_… all right, back to work now._

_—when they’re that closely tailored—_

_… I said back to_ work _!!_

_—there’s no reason he should consider any plan that would require him to wear one. Even were there an attachment point, mere cloth and stitching cannot deal with the kind of force we’re talking about here, even the kind of casually BAMF cloth that has the cheerful fortitude to follow Sherlock around wherever he goes, covering his arse._

_This chapter is completely implausible and I apologise. My readers deserve better._

_As for you Sherlock: if you’re going to display this kind of casual attitude to canon compliance—leading poor John astray, too, for shame!—I’m not even going to try to save you anymore. You don’t want my help?_

_Fine, then. You asked for it._

_Bare concrete. No tricks. No deus ex machina. No interruption of the narration. No missing scenes conveniently spliced in five years before the present day which mess confusingly with the old timeline and do very little to clarify the point. Ahem. Nothing extra-canon to slow the fall_ at all _._

 _And certainly no leeway in_ this _fandom for the use of dramatic effect._

 _That burn was just a warning shot:_ this _is what happens when you piss off your author._

 _You’re so in love with your physics, Sherlock? Well, we’ll let_ physics _sort out what happens when a seventy kilogram sack of ungrateful meat and fragile bone hits the ground._

_Not so chatty now, are you?_

_Final take; white rabbits, can’t say back forever. Places, please—stop grinning like that, Sherlock, have you not been listening to a word I’ve said?—and… action!_


	5. Take 5

John made it out the window just behind the shockwave and just ahead of the fireball, feeling a distinct lack of grenade fragments hitting him, and feeling rather happy to be alive. One step, and then he was over the railing and falling, his arms and legs spiralling like a pair of eggbeaters mixing two cakes at the same time.

But not for long.

He pulled in his arms, tucking his elbows into his ribcage, setting his chin against his chest and tensing his forearms in front of his face as a makeshift cage to protect his head. He kept his legs and feet together, hips and knees slightly bent, toes down, focussing on keeping his body loose but ready for….

Impact—the balls of John’s feet hit the ground at the same time and he absorbed a little of the force immediately, settling down onto his full foot and resisting the increasing bend to his knees. Then he threw himself to the side and let his calf take the next bit of the fall, then his thigh, then his hip, then rolled all along the latissimus dorsi muscle on the side of his back to come to a complete halt next to the wheel of a parked car, chin still tucked, arms still clutched protectively in front of his head.

“Sherlock?” he yelled, rolling up to his feet again, barely bruised despite the hard fall.

God, it had been a long time since he’d done that, but after the way they’d drilled it, it had been utterly automatic. Which was, actually, the entire point of the drilling. He may be a little out of shape now, a little heavier—but then again, he didn’t have twenty kilos of kit and a rifle dragging him down. Nor his colour sergeant yelling at him for being a disgrace to the uniform, although the threat of imminent death had provided an even larger shot of the adrenaline that had always served to sharpen John’s focus.

Where was Sherlock? If he’d bloody cracked his stupid head open on the concrete, for real this time, John was going to _kill_ him.

“Sherlock!”

Sherlock was standing a few feet away, apparently unharmed, staring up at the smoke drifting out of the windows of 221B.

“Sherlock, are you—”

“I’m fine,” Sherlock dismissed him.

Without looking at John, he strode up to the front door.

Somewhat dumbfounded, John hurried along behind as he pulled it open and inspected the inside for a moment before stepping in. The ceiling at least in here seemed intact; there was little more than a bit of cracked plaster on the walls of the hallway. Perhaps the explosive portion of the charge had been shaped, to let the shockwave blow out the windows and leave the rest to the fireball? John shook off the thought; however the device had been constructed, they were just plain lucky, apparently, that it hadn't been designed to kill them.

Mycroft was still picking himself up from the foot of the stairs, gripping one elbow with his hand, and Mrs Hudson had poked her head out of her doorway to see what was going on.

“Oh, Sherlock,” she said with a sigh of resignation. “What have you blown up this time?”

Sherlock ignored her. “Mycroft, why haven’t you got Mrs Hudson out yet?” he demanded. “I knew you were slow; I didn’t think you were _this_ slow.”

John felt this was rather missing the point. “Come on outside, Mrs H,” he said, gesturing urgently. “Some kind of advanced incendiary grenade just went off upstairs. It doesn’t look to have done too much damage, but there’s a fire and the building might be structurally compromised. We should wait outside for emergency services to clear it.”

“Ooooh, Sherlock Holmes!” their landlady scowled at him as she hurried past them both. ”You’ve no idea what you do to my insurance premiums.”

Mycroft glared at Sherlock, too—or at least looked patronisingly disdainful, which was the same thing coming from Mycroft—as he made his own way out. “You _did_ take the more direct route down, brother; it’s hardly surprising it took me a little longer to come down the stairs.”

“To _roll_ down them, you mean,” jibed Sherlock, striding alongside him. “You’re lucky you’ve got plenty of padding, if you’re _that_ opposed to legwork.”

“Well I’ve hardly had _your_ experience at falling,” returned Mycroft snidely, and shifted his torso in discomfort.

Which reminded John, driving from his mind the thought that he’d have to find a moment to check Mycroft over and make sure it was mainly his pride that was bruised.

 _Sherlock_ was….

“You’re _fine_ …” John breathed, turning back to him. “How are you fine?”

They’d made it across the road at this point and settled in to wait, huddled against the wall of the building opposite as a crowd began to gather, even though the half-hearted flames they could see at the window didn’t look as though they were going anywhere fast.

“Of course I’m fine,” frowned Sherlock, eyes searching the crowd for anyone out of place. “You’re fine, aren’t you? Why shouldn’t I be fine?”

“I’ve trained with the army!” John hissed at him, worry flashing to rage. “I was certified to fast-rope and rappel into wherever they needed a bloody doctor! We drilled that landing _every day_ at Sandhurst! How do _you_ know a Parachute Landing Fall?”

Sherlock gave him a sulky glance.

“I _did_ try to tell you about the thirteen possibilities on the rooftop,” he said. “As soon as Moriarty started babbling on about owing me a ‘fall’, Mycroft made me start training for pretty much every safe landing there was. What did you think I did with my days while you insisted on doing boring shifts at the surgery? If I hadn’t been practicing with The Flying Arenzi Twins, there’s no way I could have landed a swan-dive safely onto an airbag from that height.”

Sherlock’s eyes were fixed on 221B as a fire engine arrived and two firefighters leapt out, quickly organising the hose to spray in through the windows, while another went in search of a hydrant to tap into when the truck’s tank ran out.

Mrs Hudson hurried across the road to join the fourth firefighter, who began to look slightly harried as she spoke to him. He seemed rather relieved when she was distracted by Mrs Turner appearing from the building next door carrying a large tea tray, cups from which she and Mrs Hudson began to press upon traumatised passers by.

“I’ll admit the parkour _did_ turn out to be widely applicable,” Sherlock continued grudgingly. “But the parachute Mycroft had his quartermaster pack into the back of my coat in case Moriarty wanted to abduct me and toss me from a bit higher was very awkward." He made a sound of frustration back in his throat. "And you have no _idea_ how annoying it was learning Japanese wrestling.”

At this point, John's eyes had boggled nearly out of his head.

Mycroft looked at his brother down his nose. “The parachute was not negotiable, Sherlock. We were very lucky to have ended up executing _Lazarus_ rather than _Flying Squirrel_. Or _Twinkletoes_!” He gave a theatrical shudder.

“I liked _Twinkletoes_ ,” sulked Sherlock.

“You liked _every_ plan that didn’t involve pretending to be dead,” sighed Mycroft. “That’s why we had to have _twelve_ of them. Acrobats, wrestlers, and martial artists repeatedly show the highest survival and lowest injury rates in a difficult impact. Japanese wrestling was a logical choice to round out the set given your background in Judo.”

“True, but the places that outfit got _stuck_!” Sherlock gave an appalled squirm as though the memory made his buttocks cringe of their own accord.

John’s mouth was still a little open, staring.

Glancing over at him, Sherlock’s shoulders slumped a little.

“They weren’t _twins_ , John,” he sighed, “just similar enough to pass for it in stage makeup and matching leotards. It’s _never_ twins!”

Then he narrowed his eyes, watching his brother watching a sleek black car pull up at the kerb at the end of the block, out of the radius of stopped traffic and milling gawkers.

“Sherrinford’s security is clearly compromised,” Sherlock told Mycroft warningly, returning his flat look in equal measure. “We can’t know how far, not until we get in there. John, you’re certified to fast-rope?”

“Um.”

John tried to force his mind to reboot again past the image of Sherlock in a sumo loincloth. On a flying trapeze, hanging from the arms of two identical women in sparkling leotards, while John toiled away at the surgery seeing flu patients and writing prescriptions.

That was it; he was quitting. He was going to have to give his notice first thing tomorrow morning. He was going back to blogging and solving crime with Sherlock full time. Rosie was going to _love_ living at 221B.

After all, she was a Watson.

“Well,” John managed finally, “I’m not anymore. Certification needs renewal every six months, and at this point it’s been over six years. Why?”

“Close enough,” said Sherlock, and grinned his mad grin. “Some things remain etched in the memory—which is good, because this isn’t going to work without Lady Bracknell, here. We’re going to need to borrow a boat.”

Mycroft pinched the bridge of his nose in despair—but John just grinned back, his heart fluttering with anticipation at whatever Sherlock had planned.

Oh, this was going to be _such_ a good day.

The End.

 

_… wait._

_Wait, what? You still don’t believe me?_

_Seriously?_

_Dear God, what is it like in your funny little brains?_

_Look, here’s the thing, fine people of fandom: it was only a first floor window. My estimation says approximately a 3.5 metre fall—probably less, but let’s be generous. Following Sherlock's calculations from the first chapter through to their logical conclusion, they would have taken approximately 0.85 seconds to reach the ground by which point they would have been travelling at 8.3 m/s._

_Trust me. I (almost) topped physics. (Fucking Hung Wang. Not that I’m bitter.)_

_According to_ ~~_Mycroft_~~ _Wikipedia, a parachute will slow the jumper down to approximately 28km/hr (7.8 m/s) which is pretty bloody close to the figure above. One of the research papers linked below said the landing force experienced by a paratrooper is equivalent to a drop of between 2.7 and 3.6m, depending on the style of parachute. I can’t find a solid answer on the speed for fast roping, but you can apparently land safely (executing a good Parachute Landing Fall or PLF) while carrying only up to 25kg of kit.  Given you can parachute with up to 50kg, I’m assuming it can be faster. There’s plenty of discussions around advanced parkour forums about drops of 3.6m, and how you shouldn’t attempt this until you’re ready, and the effects of this in repetitive strain on your knees if your lower body strength or technique are inadequate._

_3.5m is a hard fall, certainly. You could easily crack your head, or break a leg or your pelvis if you hit the ground with your knees or hips locked, or break an arm that you’d instinctively thrown out to break your fall. But… it’s within the safe range of someone who knows and has practiced what to do._

_Sherlock and John were both descending feet first. When we saw them they hadn’t yet assumed the safest knees-and-hips-slightly-bent-arms-protecting-head posture for a landing—they were still caught up in escaping—but they were in perfect position to do so as soon as it wouldn’t make them look like sissies for the camera. And while they were landing on concrete—not a particularly forgiving surface—it_ was _flat, which is the most important thing, because the point is not to rely on the ground to be soft, but to absorb the excess speed by a controlled collapse, using the entire height of your body to gradually slow yourself down._

 _A PLF may not be as efficient at evenly spreading force as is landing on an equivalent height foam mattress—but no one would have been remotely worried if John and Sherlock had landed on a 1.7m thick mattress outside. You believed me when I said they were fine because trampolines had slowed them while sinking a mere half metre into the pavement, after all! (Which is true: spreading the impact evenly over 0.5 metres equates to a deceleration of 69m/s 2 or 7G for a period of .11 seconds, right on the upper limit of ‘it’s all fine’ and approaching the lower limit for human injury. This tolerance rises to 15G over the shorter peaks of deceleration associated with slowing unevenly—meaning a good PLF actually seems _less _likely to result in an injury than a perfect catch by the trampoline.)_

 _It’s_ faintly _possible that things have got a little silly in this story—and I’m not admitting to anything here; most of these theories might even work with a little bit of tweaking. The laundry trucks could have driven up onto the footpath, the trampolines could have been installed during the hiatus when no one was watching Baker Street, Anthea could have begun her descent before the boys exited the building, and for all we know Sherlock’s trousers have always had to be woven with kevlar just to keep out the fangirls. But the fact remains that if you do your physics, none of this story—nor any of the extremely entertaining theories in the comments about dragons and jetpacks and special deliveries from Acme Inc.—actually turns out to be necessary after all._

_Whether or not Sherlock attended the Mycroft School of Fall Mitigation, he and John both have many good reasons to have trained precisely what to do in a fall. If they were able to get onto that boat from a helicopter, they certainly have done._

_So: they jumped out the window. They hit the ground. They rolled. They got up again. They found Mycroft and Mrs Hudson, dusted them off, reinstalled Mrs H at her kitchen table to prevent England falling while they were otherwise occupied… and then they walked away, completely uninjured, and went off to play pirates._

_Obviously._

_And if you still don’t believe me, or my grasp of physics (and if you’ve been listening to Hung about the limitations of my abilities in that department, I wouldn’t blame you) consider this: if I’ve achieved nothing else in this story, I hope I’ve demonstrated that you can have a great deal more fun by occasionally throwing physics out the window. Even if you_ don’t _stick around to calculate how fast it falls._

 _If it’s the only way that it could have happened—and clearly we can see that it_ did _happen—then obviously that’s the way that it_ must _have happened._

 _We all know_ BBC Sherlock _is set in the real world, where you can tell an airline pilot by his thumb, where_ anyone _plugs in their phone without scratching the charger against the case, where you can take a crack shot with a pistol through glass, and where a traumatised war veteran and an antisocial drug addict could be the very best things ever to happen to each other._

_So logically, it’s a satisfyingly realistic explanation after all._

_The End. (Really)_

 

 _PS: Hung was actually a very nice guy who studied his arse off. Although it is possible that I’m still bitter about missing out on dux. I_ did _beat him in Advanced Maths, though—I beat_ everyone _in Advanced Maths (suck on THAT, Hung!)—so really, it’s all fine. I don’t need to be the best at everything. *eyelid twitches*_

_(All right, really really now.)_

**Notes for the Chapter:**

> To Aelaer for the inspiration, to Megabat for the beta, to JunkenMetel and all the other readers who've contributed thrilling theories and encouraging comments, to SherlocksSister for getting it bloody bang on the money, to Hubby for putting up with my constant requests to check something else, and to everyone else who's read and come along for the ride. I've had a lot of fun with this one. If you've had fun too, I would dearly love to hear from you!
> 
> More selected research links, among the very very (very) many:  
> [Parachute Landing Fall](https://en.wikipedia.org/wiki/Parachute_landing_fall)  
> [Some details: Fast rope vs Rappel](http://www.sleuthsayers.org/2014/09/some-details-fast-rope-vs-rappel.html)  
> [How to fall 35,000 feet and survive](http://www.popularmechanics.com/adventure/outdoors/a5045/4344036/)  
> [Sandhurst training](http://www.dailymail.co.uk/tvshowbiz/article-2033008/Wimps-need-apply-From-brutal-discipline-merciless-70km-yomps--Sandhurst-hell.html)  
> [Human crash survivability and injury tolerances](https://pdfs.semanticscholar.org/14b0/b412c17aa8bbe4f8dc5955c3d68a671a0a35.pdf)  
> [Ground reaction force and loading rates from various landing techniques](http://nzparkour.co.nz/wp-content/uploads/2014/05/GRF-and-LR-associated-with-parkour-drop-landing-techniques-from-varying-heights.pdf)  
> 


End file.
